The field of the invention pertains to machines that automatically form packages from flat blanks, fill the packages with a liquid or highly viscous material, seal the package and discharge the sealed packages for visual inspection. In particular, the invention pertains to the formation of packages from laminated and coated cardboard blanks to produce a complete sealed and sufficiently sterile enclosure for food items, the packages incorporating integral tear-off tops.
Examples of the packages to which the machines are intended are disclosed in U.S. Pat. No. 4,717,046 and German invention document DE 3143671 A1 wherein a separable tongue or top may be torn off to provide the dispensing outlet for the package, however, the disclosure below is not limited to the particular packages disclosed in these publications.
As a further example reference is made to the package with a replaceable tear-off top disclosed in applicant's pending U.S. patent application Ser. No. 07/705,354 wherein laminated flat blanks are formed into packages. In this disclosure the tear-off top is configured and sealed in a manner that permits the top to be replaced over the dispensing outlet after it is torn off.
U.S. Pat. No. 3,382,644 illustrates a bag forming and filling machine. In this machine the bags or packages after forming on a separate apparatus are raised on fixtures to insert nozzles of the filling apparatus into the packages and the packages are filled before the packages are again lowered. Belgian invention publication No. 547082 discloses a package forming and filling sequence wherein the packages are formed by folding a blank up around an upper mandrel. The package rests on a second mandrel through a side sealing station and a filling station, the upper mandrel having been withdrawn to permit filling. The open top formed packages are filled from hoppers that travel with the packages. The hoppers have filling tubes depending therefrom which enter the packages during the filling operation.
Belgian invention publication No. 538036 discloses the use of an upper former or mandrel that drives a blank down into a die. As the bottom portion of the blank is driven down into the die and the package sides partially folded up toward the upper former, a lower former or mandrel moves up into the die to meet the package bottom. The two formers then proceed downward through the die to form the package. Below the die the package proceeds between rotating side sealers and the formers retract allowing the side sealed package to be blown into a chute as it drops from the side sealers.
The machine disclosed in U.S. Pat. No. 4,669,253 forms a package similar to the Belgian disclosures, however, this disclosure provides two significant differences. Firstly, the bottom forming surfaces of the upper and lower mandrel are complementary and the edges of these surfaces register with the upper edges of the die cavity to form the package sidewalls by defining pronounced boundaries between the clamped bottom portion of the package blank and the adjacent outer portions of the package blank. To accomplish these pronounced boundaries, the curvature of the upper edges of the die cavity matches the curvature of the edges of the complementary former surfaces. In the forming cycle the formers come together at exactly the top edge of the die cavity with the package blank therebetween before descending through the die cavity.
Secondly, in U.S. Pat. No. 4,669,253 the package blank is driven through the die and into a fixture. The fixture is indexed from station to station for sealing the package sides, filling the package and top sealing the package. The package is raised from the fixture for side sealing and again raised from the fixture for filling the package. The package is pushed through the fixture and supported from the bottom for top sealing and discharge from the machine below the fixture.
U.S. Pat. No. 4,252,052 discloses a similar package forming machine, however, this machine differs in three significant ways. First, this machine lacks a lower former or mandrel. Second, the lower die comprises two opposed downwardly curving plates that are completely open to allow the package edges to remain apart. Third, the package edges are air heated to activate the sealant before the edges are clamped together. The air heater is inserted between the package edges before the edges are clamped together.
The formation of pouch type packages from coated paper board blanks requires careful and accurate folding and sealing. The open package must then be transported for dosing or filling with product and finally positioned for sealing of the filled package. With a view toward avoiding unnecessary movement of the package through the forming, filling and sealing cycle, applicant has developed the machine and method disclosed below.